Service Controller

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Introduction

Controlling services from code has never been so easy. The .NET framework has taken the cumbersome task of wrapping the Windows API calls that we traditionally used to control services.

Using the code

First, let's get a list of services running on the machine. To do this, we will call the static method GetServices() of the System.ServiceProcess.ServiceController class.

//create an array to hold the list of services
System.ServiceProcess.ServiceController[] services;
//fill the array with the GetServices method
services = System.ServiceProcess.ServiceController.GetServices();

In my application, I load a ComboBox with the list of services running on the machine. To make life easy, I create a DataTable on the fly and add records to it to represent the individual services. Then I bind the DataTable that I created to the ComboBox. I also take some additional steps to sort the data in the DataTable and to add an initial ComboBox entry that prompts the user to "Select A Service".

//Add columns to the DataTable
_tblServices.Columns.Add( new DataColumn( "ServiceName", typeof( System.String ) ));
_tblServices.Columns.Add( new DataColumn( "DisplayName", typeof( System.String ) ));
_tblServices.Columns.Add( new DataColumn( "Index", 
                              typeof( System.Int32 ) )); //used for sorting

System.ServiceProcess.ServiceController[] services;
services = System.ServiceProcess.ServiceController.GetServices();

foreach( System.ServiceProcess.ServiceController controller in services )
{
   DataRow row = _tblServices.NewRow();
   row["ServiceName"] = controller.ServiceName;
   row["DisplayName"] = controller.DisplayName;
   row["Index"] = 1;

   _tblServices.Rows.Add( row );
}

//add a dummy row
DataRow blankRow = _tblServices.NewRow();
blankRow["ServiceName"] = string.Empty;
blankRow["DisplayName"] = "<Select A Service>";
blankRow["Index"] = 0;
_tblServices.Rows.Add( blankRow );

//use a DataView to sort the entries. I use the "Index" 
//Column to force my blank record to the top
DataView view = new DataView( _tblServices, string.Empty, 
                    "Index, DisplayName", 
                    DataViewRowState.CurrentRows );
cbServices.DataSource = view;
cbServices.ValueMember = "ServiceName";
cbServices.DisplayMember = "DisplayName";

//Assign an event handler to the selectedValueChanged Event
cbServices.SelectedValueChanged += 
           new EventHandler(cbServices_SelectedValueChanged);

In the previous code, the ComboBox was assigned an event handler. The SelectedValueChanged event will allow me to update the GUI according to the status of the selected service. In order to get the status of the service I instantiate a new ServiceController object and pass in the Service Name. Then I enable/disable each button depending on the current service status.

private void cbServices_SelectedValueChanged(object sender, System.EventArgs e)
{
    ServiceController controller = GetService();

    if( controller != null )
        UpdateControls( GetService() );
    else
    {
        statusBar1.Text = string.Empty;
        btnStart.Enabled = false;
        btnStop.Enabled = false;
        btnPause.Enabled = false;
        btnContinue.Enabled = false;
    }
}

//Updates the buttons according to the currently selected service
void UpdateControls( ServiceController controller )
{
    btnPause.Enabled = ( controller.Status == ServiceControllerStatus.Running 
                                 && controller.CanPauseAndContinue == true );
    btnStop.Enabled = ( controller.Status == ServiceControllerStatus.Running 
                                             && controller.CanStop == true );
    btnContinue.Enabled = ( controller.Status == ServiceControllerStatus.Paused 
                                 && controller.CanPauseAndContinue == true );
    btnStart.Enabled = controller.Status == ServiceControllerStatus.Stopped;
    statusBar1.Text = "Status: " + controller.Status.ToString();
}

//Gets the currently selected service
private ServiceController GetService()
{
    if( cbServices.SelectedValue.ToString().Trim() != string.Empty )
        return new ServiceController( (string)cbServices.SelectedValue );
    else
        return null;
}

If you are familiar with services you are probably aware that some services can not be stopped or paused. This can be checked by accessing the CanPauseAndContinue property and the CanStop property of the ServiceController class. Since my UpdateControls() method checks these properties I don't have to check these properties again during the button Click events.

private void btnStop_Click(object sender, System.EventArgs e)
{
    System.ServiceProcess.ServiceController controller = GetService();
    controller.Stop();
    WaitForStatus( controller, ServiceControllerStatus.Stopped, 
                                        new TimeSpan( 0,1,0) );
    UpdateControls( controller );
}

private void btnStart_Click(object sender, System.EventArgs e)
{
    System.ServiceProcess.ServiceController controller = GetService();
    controller.Start();
    WaitForStatus( controller, ServiceControllerStatus.Running, 
                                        new TimeSpan( 0,1,0) );
    UpdateControls( controller );
}

private void btnPause_Click(object sender, System.EventArgs e)
{
    System.ServiceProcess.ServiceController controller = GetService();
    controller.Pause();
    WaitForStatus( controller, ServiceControllerStatus.Paused, 
                                       new TimeSpan( 0,1,0) );
    UpdateControls( controller );
}

private void btnContinue_Click(object sender, System.EventArgs e)
{
    System.ServiceProcess.ServiceController controller = GetService();
    controller.Continue();
    WaitForStatus( controller, ServiceControllerStatus.Running, 
                                        new TimeSpan( 0,1,0) );
    UpdateControls( controller );
}

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